Electric lamp



arch 31, 1942." MACKSOUD 2,277,876

ELECTRIC LAMP Filed Nov 9, 19:5 2 Sheets-Sheet 1 M. E. MACKSOUD ELECTRIC LAMP 2 Sheets-Sheet 2 Filed NOV. 9, 1958 Patente err. 33, 1942 ELECTRIC i .Michel E. Macksoud, Gloucester, Mass.

Application November 9, 1938, Serial No. 239,638

7 Claims.

This invention relates to electric illuminating terior arc tube curved to provide maximum length in minimum space and to conform in shape and size to an associated filament, which in turn is curved to conform with the reflecting walls of the bulb. The are and filament emit complementary light rays, and the arc operates more efiiciently through being exposed to direct rays lamps and in one aspect relates more particularly from the filament and to rays reflected from the filament by the reflecting walls of the bulb.

- Anotherfeature of the invention resides in coating the interior surface of the bulb of an electric arc lamp with a substance which fluoresces under ultra-violet light from the arc, and

' in providing at the exterior of the bulb a reflector for reflecting the ultra-violet light penetrating the coating and the bulb walls, upon the back side of the coating so that both sides fluoresce through exposure to the ultra-violet lamp and thus provide efiiciently, visible light from invisible light.

Another feature of the invention resides in connecting the ionizing electrodes of an arc tube in series with a cooperating filament, and in connecting a condenser across this series connection for establishing the arc at'a lower potential than has formerly been possible.

An object of. the invention is efiiciently to produce visible, artificial light having desired characteristics.

Another object of the invention is efficiently to produce and to combine the light from several sources in a single bulb for providing visible, artificial light having desired characteristics.

Other objects of the invention with be apparent from the following description and from the drawings.

The invention will now be described with'reference to the drawings, of which:

Fig. 1 is a view in elevation of a lamp embodying this invention, portions of the bulb being shown as broken away;

Fig. 2 is a projected view of the lamp of Fig. 1;

Fig. 3 is a diagrammatic view of an arc tube, filament and condenser circuit in which the lamp of Figs. 1 and 2- may be connected, and

Fig. 4 is a view in side elevation of the arc tube of the lamp of Fig. 1.

The lamp includes a bulb 40 of conventional shape having all or a portion of its interior surface coated with a substance 4| such for example, as eosine, naphalin, etc., which fiuoresces under ultra-violet light to produce visible light. The outer surface of the bulb adjacent the coatings 6| has a surface 42 of aluminum or other material which efficiently reflects ultra-violet and visible light. n

The bulb 40 includes in its structure, the hollow mount 36 terminating in a solid press and containing the usual exhaust tube. The curved gas discharge or are tube 3 is supported within the bulb by the lead wires 28 and 29, the upper.

ends of which are sealed within the press of the mount 36. The tube 3 contains mercury or other metallic vapor and includes a circular or arcuate portion extending along a circular path and terminating in the enlarged end portions 5 and l which are disposed at substantially the same level in the bulb 40. The lower ends of thelead wires 28 and 29 extend into and are sealed in the portionsi and l and are provided with the coiled electrodes 20 and 19 which are located substantially on the axis of the tube 3. A starting electrode I1 is sealed into the inner wall of the tube adjacent the electrode 20 and is provided with the lead wire 25 which also is sealed into the press of the mount 35.

The are tube 3 is provided with an elongated tube or appendix 3| of small diameter sealed sub:- stantially mid-way into the upper wall of the tube. The appendix 3i has a constricted neck and extends substantially above the arc tube. Its purpose is to .ballast or equalize the metallic vapor pressure within the arc tube. A portion of the mercury vaporized during the operation of the lamp escapes into the appendix 3| where it is condensed as at 33 and momentarily retained by friction or capillary action. This prevents the vapor pressure in the tube 3 from rising above a desired maximum. The condensed vapor eventually drains'back into the tube 3 to vaporize again and if the pressure again rises unduly, to enter again the appendix 3|. By thus balancing the vapor pressure within the gas discharge tube, the light intensity of the arc is maintained substantially constant.

The shield 34 preferably formed from reflecting metal is supported in the bulb 40 between the upper end of the appendix 3| and the press of the mount 36, and is secured to an insulating panel 35 through which the lead wires 22, 24, 26, 28 and 29 are conducted. The shield is supported from the upper end of the appendix 3| by the wire 21 and performs the functions of reflecting light rays tending to enter the neck of the bulb, and to protect the press of the mount from the heat generated within the bulb.

The curved portion of the tube 3 has the lower protrusions 8 in which are sealed the small wires II for supporting the filament 9 equidistantly below the tube 3 to conform in shape and size to the axis of the tube.

The filament 9 is connected by the lead wires 22 and 24 to the electrode I9, the starting resistance 38 and the lamp terminals as shown by Fig. 3. The resistance 38 is coiled around the exhaust stem in the mount 36 and is so connected as shown'byFig. 3 as to be ineffective when the arc is established between the main electrodes l9 and 20. j

The lamp is also provided with a condenser 44 which is coiled around the exhaust tube of the lamp between the resistance 33 and the exhaust tube. The condenser is connected to one side of the filament 9 and to the electrode 20 and to the tube terminals as shown by Fig. 3, and serves to build up a charge having a potential sufficient to establish a starting arc between the electrodes I1 and 20, which are ionizes the gas within the tube 3 for establishing the main are between the electrodes l9 and 20.

The filament 9 and are tube 3 are so located with respect to each other and to the reflecting surface'42 that the gas discharge tube is exposed over its entire area to direct rays from the filament and to rays reflected from the filament by the reflecting surface 42.. The effect of this is to cause the arc to be propagated under conditions of high and uniform temperature with resulting increase in intensity and efliciency. The reflecting surface also acts to prevent heat losses from the lamp and by this aids further in maintaining a high are temperature as well as resisting tem-' perature changes caused by conditions exterior the lamp. As shown by Fig. 3, the arc tube 3 curves substantially concentrically with the walls of the bulb 40 through an arc of substantially 240, this resulting in the tube being in the focal area of a major portion of the reflecting surface of the lamp resulting in maximum reflecting effect.

The presence of the reflecting surface, and in this case preferably-upon the outside of the bulb, makes it possible to add to the efliciency of the lamp by the generation of visible light by the action of ultra-violet light upon the fluorescent coating 4|, preferably on the inside of the bulb. The are to a large extent and the filament to a less extent, emit ultra-violet light which causes the fluorescent coating 4| to glow to emit visible light. The inner surface of the coating 4| is ex-' posed to the direct rays from the filament and the arc but the rays pass between particles of the coating to be reflected by the reflecting surface 42 to strike the outer or back surface of the coating 4| to cause both sides of the coating to glow at visible light frequencies, thus adding to the efilciency of the lamp.

The electrodes l9 and 20 are preferably coated with equal proportions of barium and strontium carbonates with a trace of caesium. This provides long life and high electron emission.

The rays from the filament, arc and the coating of fluorescent material are reflected by the surface 42 in substantially parallel rays through the non-reflecting lower portion l2 of the lamp.

Having thus disclosed my invention and described a preferred embodiment thereof, but without intending to limit it to the details of construction shown, I claim and desire to secure by Letters Patent:

1. An electric illuminating lamp comprising a bulb, a curved elongated gas discharge tube located concentrically within the bulb with its ends at the same level in the bulb and being' curved substantially in the arc of a circle with its axis lying in a plane disposed substantially at right angles to the longitudinal axis of the bulb, and a filament in circuit with said tube and curved to conform longitudinally therewith.

2. An electric illuminating lamp comprising a bulb, having a curved elongated gas discharge tube located concentrically therein with its ends at the same level in the bulb and being curved substantially in the arc of a circle with its axis located in a plane disposed substantially at right angles to the longitudinal axis of the bulb, and a filament in the bulb connected in series withthe tube and curved to conform to said tube throughout its length.

3. An electric illuminating lamp comprising a bulb, having a curved elongated gas discharge tube located therein with its ends at the same level in the bulb and being curved substantially in the arc of a circle with its axis lying in a plane disposed substantially at right angles to the longitudinal axis of said bulb, and a filament supported substantially equi-distant at a plurality of points from the surface of said tube and being curved to conform to the tube throughout its length.

4. An electric illuminating lamp comprising a bulb, having terminals for connection to a source of electric energy, an elongated curved arc tube having electrodes, said tube being curved substantially in the arc of a circle with its axis lying in a plane disposed substantially at right angles to the longitudinal axis of said bulb and both ends disposed at substantially the same, level in the bulb, a filament supported adjacent to said tube and being curved to conform thereto throughout its length, and connections connecting said electrodes and said filament in series to said terminals.

5. An electric illuminating lamp comprising a bulb, having terminals for connection to a source of electric energy, an elongated curved arc tube having electrodes, said tube being curved substantially in the arc of a circle and mounted in the bulb in a plane disposed substantially at right angles to the axis of the bulb and both of its ends disposed at substantially the same level in the bulb, a filament supported by projections from the exterior surface of the tube at a plurality of spaced points and conforming in outline to the curvature of the tube throughout its length, and connections connecting said electrodes and said filament in series to said terminals.

6. An electric lamp comprising a bulb, means for producing visible and ultra-violet light including a curved arc tube and a concentrically curved filament disposed adjacent to the arc tube and curved to conform concentrically thereto throughout its length and connected in series therewith, a coating of fluorescent material on a portion of the inner surface of the bulb, and a reflector located upon the outer surface of the bulb opposite said coating.

7. An electric illuminating lamp comprising a pear shaped bulb, having a reflecting coating upon a limited portion of its area, a gas discharge tube curved in substantially 240 of a circular arc and mounted within the coated portion of the 10 MICHEL E. MACKSOUD. 

